Hi All,Newbie to screen printing, but I've done a bit of research... obviously this isn't enough...here is my screen created:

the red circles highlight where the emulsion hasn't washed out... why is this?

I'm using a 500W bulb at a distance of 16"I've exposed for 11mins/14mins on a variety of tests but the same problem is repeated every time..I've tried double printing the imageI've also tried layering up to 3 layers of printed acetate which doesn't let any light through...

could it be the lines are too thin?? to give an idea of scale the width of the "HAPPY BIRTHDAY!!!" is 70mm, the total heights is about 80mmany thoughts are much appreciated!!!